What software is compatible with the hardware that you have available;

Preferences between proprietary and open software;

Any discipline-specific norms (and the associated peer-to-peer support that comes with them).

You may choose certain formats during data collection and analysis but others for preservation - for example, by converting your data to standard or open formats.

What formats do data centres expect?

You may choose or be required to submit your data to a data centre. They may convert your data to a preferred format for preservation. It's worth thinking how these decisions may affect your ability to access and re-use your data in the future.

The UK Data Archive list of preferred formats gives an indication of standards to which data centres typically work.